Microplastics as potential barriers to ultraviolet light emitting diode inactivation of MS2 bacteriophage: Influence of water-quality parameters

Microplastics have emerged as a concerning contaminant in drinking water sources, potentially interacting with pathogenic microorganisms and affecting the disinfection processes. In this study, MS2 was selected as an alternative for the human enteric virus. The influence of microplastics polyvinylchloride (MPs -PVC) on ultraviolet light emitting diode (UV -LED) inactivation of MS2 was investigated under various water chemistry conditions, such as MPs -PVC concentration, pH, salinity, and humic acid concentration. The results revealed that higher concentrations of MPs -PVC led to the reduced inactivation of MS2 by decreased UV transmittance, hindering the disinfection process. Additionally, the inactivation efficiency of MS2 in the presence of MPs -PVC was influenced by pH, and acidic solution (pH at 4, 5, and 6) exhibited higher efficiency compared to alkaline solution (pH at 8 and 9) and neutral solution (pH at 7). The low Na+ concentrations (0-50 mM) had a noticeable effect on MS2 inaction efficiency in the presence of MPs -PVC, while the addition of Ca2+ posed an insignificant effect due to the preferential interaction with MPs -PVC. Furthermore, the inactivation rate of MS2 initially increased and then decreased with increasing the concentration of humic acid, which was significantly different without MPs -PVC. These findings shed light on the complex interactions between MPs -PVC and MS2 in the UVLED disinfection process under various water -quality parameters, contributing to drinking water safety and treatment.